Regnellidium diphyllum is considered as endangered, occurring in the State of Rio Grande do Sul, Brazil, and a few adjoining localities in Uruguay, Argentina and the State of Santa Catarina. It grows in wetlands frequently altered for agricultural activities. Herbicides based on 2,4-dichlorophenoxyacetic acid (2,4-D) are widely used in these fields. The effects of 2,4-D on the germination of megaspores and initial sporophytic development of R. diphyllum were in-

The present study evaluated the genotoxic effects of the atmospheric air on Tradescantia pallida var. purpurea in urban areas with different intensities of vehicular traffic and in riparian forest fragments in the Sinos River Basin (Rio Grande do Sul, Brazil), considering the influence of climatic conditions prevailing in these environments. Bimonthly, from May 2012 to March 2013, cuttings with flower buds were exposed for 8 h in urban and riparian forest environments in the municipalities of Caraá, Taquara and Campo Bom in the upper, middle and lower sections, respectively, of the Sinos River Basin. Simultaneously, negative controls were made and climatic data were recorded. Micronuclei (MCN) frequencies were determined in young tetrads of pollen mother cells and expressed as MCN/100 tetrads. Significantly higher MCN frequencies were observed in buds exposed in urban and riparian forest environments in Taquara (up to 7.23 and 4.80, respectively) and Campo Bom (up to 4.90 and 4.23, respectively) than in buds exposed in Caraá (up to 2.90 and 2.50, respectively), in the majority of samplings, and in relation to the negative control (up to 1.93) in all months. Over the course of the period monitored, there were significant variations in MCN frequencies at all sampling points, with the exception of the urban environment in Caraá. For the urban environments, relation between the MCN frequency, vehicular traffic and mean temperature was observed. For the riparian forest fragments, there was no association between MCN frequency and climatic factors. Tradescantia pallida var. purpurea can be considered a useful tool to point out areas with increased atmospheric pollution, since the exposure of plants under severe climatic conditions is avoided to minimize their negative influence on the formation of micronuclei.Keywords: abiotic factors, vehicular emissions, bioindicator, environmental quality, micronucleus. Biomonitoramento do potencial genotóxico do ar em

Regnellidium diphyllum Lindm. is a heterosporous fern growing in wetlands and humid soils that are being converted to agricultural activities. Many products that are used in agriculture contain copper, resulting in surface and groundwater contamination. Germination and initial development tests were performed using Meyer's solution containing copper sulphate at concentrations of 0 (control), 1, 5, 10, 50 and 100 mg L −1 . Th e experiment was conducted in a growth chamber at 25 ± 1°C for 28 days, with a 12/12-hour light/dark cycle and a photon fl ux density of 100 μmol m −2 s −1. Th e lowest germination rate (6%) was observed at 100 mg L −1 . Primary root growth was signifi cantly reduced at ≥ 10 mg L −1 . Secondary leaves of sporophytes grown in concentrations ≥ 5 mg L −1 were progressively shorter than were those formed by the control plants. We conclude that the release of pollutants containing copper into the natural habitats of R. diphyllum can cause phytotoxicity, threatening the establishment of populations and worsening the already vulnerable conservation status of this species.

The Tradescantia micronucleus (Trad-MCN) bioassay was used to investigate genotoxicity of water bodies in the Parque Municipal Henrique Luís Roessler (PMHLR), a conservation unit in the city of Novo Hamburgo, Southern Brazil, from November 2010 to October 2011. Every month, cuttings with young inflorescences of Tradescantia pallida var. purpurea were exposed for 24 hours to water collected at three sites in the park: (S1) head of the main stream; (S2) head of a secondary stream; (S3) a point past the junction of the two water bodies in which S1 and S2 were located. As a negative control, cuttings were exposed to distilled water for 24 h every quarter. Micronuclei (MCN) frequency was determined in young tetrads of pollen mother cells and described as MCN/100 tetrads. Rainfall data were also recorded. In nine months at S1 and S2, and in eleven months at S3, micronuclei frequencies were significantly higher than in quarterly controls, in which frequencies varied from 1.19 to 1.62. During sampling, no significant differences were found in MCN frequencies at S1, which ranged from 2.2 to 3.6. At the other sampling sites, there were significant differences between the months evaluated, and MCN frequencies ranged from 1.3 to 6.5 at S2 and from 2.3 to 5.2 at S3. There were no associations between rainfall and MCN frequencies at the three sampling sites. Tradescantia pallida var. purpurea confirmed genotoxicity in the water bodies of the PMHLR, even at the head of the streams, which suggests that actions should be promoted to control anthropogenic effects in the streams of this conservation unit. Keywords

This study assessed the genotoxicity and chemical quality of the Rio dos Sinos, southern Brazil. During two years, bimonthly, cuttings of Tradescantia pallida var. purpurea with flower buds were exposed to river water samples from Caraá, Santo Antônio da Patrulha, Taquara and Campo Bom, which are municipalities located in the upper, middle and lower stretches of the Rio dos Sinos basin. Simultaneously, chemical parameters were analyzed, rainfall data were surveyed and negative (distilled water) and positive (0.1% formaldehyde) controls were made. Micronuclei (MCN) frequencies were determined in tetrads of pollen grain mother cells. From the upper stretch toward the lower, there was an increase in the frequency of MCN and in concentrations of chemical parameters. Cadmium, lead, copper, total chromium and zinc were present at the four sites and a concentration gradient was not demonstrated along the river. The multivariate analysis revealed that two principal components exist, which accounted for 62.3% of the observed variances. Although genotoxicity was observed in Santo Antônio da Patrulha, the water presented higher mean values for most of the assessed parameters, in the lower stretch, where urbanization and industrialization are greater. The spatial and temporal pattern of water quality observed reinforces the importance of considering the environmental factors and their effects on organisms in an integrated way in watercourse monitoring programs.